U.S. patent application number 12/100681 was filed with the patent office on 2009-06-25 for a-arm frame with bearing for hauling devices.
This patent application is currently assigned to ROLLER BEARING COMPANY OF AMERICA, INC.. Invention is credited to Brian Gaumer.
Application Number | 20090160151 12/100681 |
Document ID | / |
Family ID | 40787683 |
Filed Date | 2009-06-25 |
United States Patent
Application |
20090160151 |
Kind Code |
A1 |
Gaumer; Brian |
June 25, 2009 |
A-ARM FRAME WITH BEARING FOR HAULING DEVICES
Abstract
An A-arm frame 10 for a vehicle has two arms 12, 14 that
converge at an apex 16. Each arm has a mounting end opposite the
apex for mounting to the housing for an axle of the vehicle. A
pivot joint at the apex connects the A-arm frame to the vehicle
frame. The pivot joint includes a case-hardened spherical plain
bearing 22 that includes an inner ring 26 and an outer ring 28. The
inner ring 26 may have a lubrication aperture therethrough, but the
outer ring 28 has no lubrication aperture therethrough. The outer
ring 28 may have a multi-fracture configuration and, therefore, a
greater wrap-around of the inner ring 26 than it otherwise would
have.
Inventors: |
Gaumer; Brian; (Watertown,
CT) |
Correspondence
Address: |
MICHAUD-DUFFY GROUP LLP
306 INDUSTRIAL PARK ROAD, SUITE 206
MIDDLETOWN
CT
06457
US
|
Assignee: |
ROLLER BEARING COMPANY OF AMERICA,
INC.
Oxford
CT
|
Family ID: |
40787683 |
Appl. No.: |
12/100681 |
Filed: |
April 10, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61014915 |
Dec 19, 2007 |
|
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|
Current U.S.
Class: |
280/124.1 ;
384/286 |
Current CPC
Class: |
B60G 9/02 20130101; B60G
2200/30 20130101; F16C 2223/12 20130101; F16C 2226/62 20130101;
B60G 7/005 20130101; B60G 2206/13 20130101; B60G 2204/143 20130101;
B60G 2204/148 20130101; F16C 33/102 20130101; F16C 2326/05
20130101; B60G 2204/416 20130101; F16C 11/0614 20130101; B60G 7/001
20130101; F16C 33/14 20130101 |
Class at
Publication: |
280/124.1 ;
384/286 |
International
Class: |
B60G 9/00 20060101
B60G009/00; F16C 33/10 20060101 F16C033/10 |
Claims
1. An A-arm frame for joining an axle housing to a vehicle frame,
the A-arm frame comprising two arms that converge at an apex, each
of the arms having a mounting end opposite from the apex for
mounting to the axle housing, the A-arm frame further having a
pivot joint at the apex for connecting the A-arm frame to the
vehicle frame, the pivot joint comprising a spherical plain bearing
that comprises an inner ring and an outer ring; wherein the
spherical plain bearing is a case-hardened bearing.
2. The A-arm frame of claim 1, wherein the inner ring and the outer
ring that each have a surface hardness of at least about Rockwell
C56 and a core hardness of not more than about Rockwell C49.
3. The A-arm frame of claim 2, having an effective case of about
0.5 millimeters to about 1.6 millimeters from the surfaces of the
inner ring and the outer ring.
4. The A-arm frame of claim 1, wherein the inner ring and the outer
ring that each have a surface hardness of about Rockwell C56 to
about Rockwell C59 and a core hardness of about Rockwell C30 to
about Rockwell C49.
5. The A-arm frame of claim 4, having an effective case of about
0.5 millimeters to about 1.6 millimeters from the surfaces of the
inner ring and the outer ring.
6. The A-arm frame of claim 1, wherein the inner ring has a convex
bearing surface that conforms to a spherical diameter of about 134
mm and a shaft bearing surface having a diameter of about 100 mm,
and the outer ring has an outside diameter of about 150 mm; and
wherein the inner ring and the outer ring that each have a surface
hardness of at least about Rockwell C56 and an effective case of
about 0.5 millimeters to about 1.6 millimeters from the surfaces of
the inner ring and the outer ring.
7. The A-arm frame of claim 6, wherein the inner ring and the outer
ring that each have a core hardness of not more than about Rockwell
C49.
8. The A-arm frame of claim 1, wherein the outer ring has no
lubrication aperture therethrough.
9. The A-arm frame of claim 1, wherein the outer ring has a
multi-fracture configuration.
10. The A-arm frame of claim 1, wherein the outer ring has a double
fracture configuration.
11. The A-arm frame of claim 1, wherein the pivot joint comprises a
linking pin in the inner ring, the linking pin having a lubrication
supply conduit.
12. The A-arm frame of claim 11, wherein the inner ring includes a
lubrication groove and the lubrication supply conduit permits a
lubricant to pass from the linking pin to a linkage load zone
between the linking pin and the inner ring.
13. The A-arm frame of claim 12, wherein the inner ring includes an
aperture extending radially therethrough, the aperture permitting
lubricant to pass from the linkage load zone to a bearing load zone
between the inner ring and the outer ring.
14. In a vehicle comprising a vehicle frame, an axle having an axle
housing and an A-arm frame joining the axle housing to the vehicle
frame, the A-arm frame comprising two arms that converge at an
apex, each of the arms having a mounting end opposite from the apex
for mounting to the housing for an axle of the vehicle, the A-arm
frame further having a pivot joint at the apex for connecting the
A-arm frame to the vehicle frame, the pivot joint comprising a
spherical plain bearing, and the spherical plain bearing comprising
an inner ring and an outer ring; the improvement comprising that
the spherical plain bearing is a case-hardened bearing.
15. The vehicle of claim 14, wherein the inner ring and the outer
ring that each have a surface hardness of at least about Rockwell
C56 and a core hardness of not more than about Rockwell C49.
16. The vehicle of claim 15, having an effective case of about 0.5
millimeters to about 1.6 millimeters from the surfaces of the inner
ring and the outer ring
17. The vehicle of claim 14, wherein the inner ring and the outer
ring that each have a surface hardness of about Rockwell C56 to
about Rockwell C59 and a core hardness of about Rockwell C30 to
about Rockwell C49.
18. The vehicle of claim 17, having an effective case of about 0.5
millimeters to about 1.6 millimeters from the surfaces of the inner
ring and the outer ring
19. The vehicle of claim 14, wherein the inner ring has a convex
bearing surface that conforms to a spherical diameter of about 134
mm and a shaft bearing surface having a diameter of about 100 mm,
and the outer ring has an outside diameter of about 150 mm; and
wherein the inner ring and the outer ring that each have a surface
hardness of at least about Rockwell C56 and an effective case of
about 1.1 millimeters to about 1.6 millimeters from the surfaces of
the inner ring and the outer ring.
20. The vehicle of claim 19, wherein the inner ring and the outer
ring that each have a core hardness of not more than about Rockwell
C49.
21. The vehicle of claim 14, wherein the outer ring has no
lubrication aperture therethrough.
22. The vehicle of claim 14, wherein the outer ring has a
multi-fracture configuration.
23. The vehicle of claim 14, wherein the outer ring has a double
fracture configuration.
24. The vehicle of claim 14, wherein the pivot joint comprises a
linking pin in the inner ring, the linking pin having a lubrication
supply conduit.
25. The vehicle of claim 24, wherein the inner ring includes a
lubrication groove and the lubrication supply conduit permits a
lubricant to pass from the linking pin to a linkage load zone
between the linking pin and the inner ring.
26. The vehicle of claim 14, wherein the inner ring includes an
aperture extending radially therethrough, the aperture permitting
lubricant to pass from the linkage load zone to a bearing load zone
between the inner ring and the outer ring.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. provisional
application No. 61/014,915 filed Dec. 19, 2007, which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to bearings in vehicles and in
particular to spherical plain bearings for A-arm frames.
BACKGROUND
[0003] Vehicles used for hauling large loads, such as those used in
mining operations, are often equipped with rigid A-arm frames that
connect their rear drive axles to the vehicle frames. The A-arm
frame consists of two arms that are fixedly mounted onto the rear
drive axle of the haul vehicle. The A-arm frame arms extend from
the drive axle housing and converge together at an apex where a
pivot joint is located. This pivot joint connects the A-arm and the
axle housing to the vehicle frame. The pivot joint contains a
spherical plain bearing that allows upward, downward, and
side-to-side relative rotation between the support frame of the
haul vehicle, the A-arm frame and the axle housing.
SUMMARY OF THE INVENTION
[0004] The present invention resides in one aspect in an A-arm
frame for joining an axle housing to a vehicle frame, the A-arm
frame including two arms that converge at an apex. Each of the arms
has a mounting end opposite from the apex, for mounting the A-arm
frame to the housing of an axle of the vehicle. There is a pivot
joint at the apex for connecting the A-arm frame to the vehicle
frame. The pivot joint includes a case-hardened spherical plain
bearing that has an inner ring and an outer ring.
[0005] The invention relates in another aspect to a vehicle
comprising a vehicle frame, an axle having an axle housing and an
A-arm frame as described herein. The A-arm frame is connected to
the vehicle frame at the pivot joint via a linking pin in the
spherical plain bearing. The A-arm frame is also connected to the
axle housing at the mounting ends of the arms.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a schematic plan view of an A-arm frame containing
a bearing according to one embodiment of the present invention;
[0007] FIG. 2 is an enlarged schematic cross-sectional view of a
portion of the A-arm frame of FIG. 1;
[0008] FIG. 3 is a partial schematic cross-sectional view of a
prior art bearing used in the A-arm frame of FIG. 1;
[0009] FIGS. 4A and 4B are schematic cross-sectional views of the
bearing shown in FIG. 2; and
[0010] FIG. 5 is a perspective view of the A-arm frame of FIG. 2
mounted to an axle housing of a haul vehicle and connected to a
vehicle frame.
DETAILED DESCRIPTION OF THE INVENTION
[0011] As shown in FIG. 1 an A-arm frame generally designated by
the reference numeral 10 for use on a haul vehicle (not shown) has
two arms 12, 14. Each of the arms has a mounting end 12a, 14a for
mounting the A-arm frame 10 to the housing 40 (FIG. 5) for the rear
drive axle of the vehicle. The arms 12, 14 converge at an apex 16
where a pivot joint 18 is mounted to connect the A-arm frame to the
vehicle frame 50 (FIG. 5). A linking pin 20 provides a connection
point for the vehicle frame, and the pin is rotatable and can slide
axially (side-to-side) in the pivot joint 18.
[0012] As shown in FIG. 2, the linking pin 20 is mounted in a
bearing 22 according to one specific embodiment of the present
invention which is described more fully below. The linking pin 20
is equipped with a lubrication supply conduit 24 through which
lubricant is provided to the interior of the bearing 22. To
assemble the pivot joint 18 into the A-arm frame 10, the bearing 22
is pressed into a bearing seat (unnumbered) in the apex 16 and is
secured therein by a retainer 52. The linking pin 20 is then
pressed through the bearing 22.
[0013] A conventional bearing 122 that has previously been used in
A-arm frame 10 in the place of the bearing 22 has, as seen in FIG.
3, an inner ring 126 and an outer ring 128 both made from high
strength, through-hardened AISI E52100 (100Cr6) steel. The outer
ring 128 has a lubrication aperture 129 therethrough and an
exterior circumferential lubrication groove 131. The outer ring 128
is a single-fracture ring, and the axial ends 133, 135 of the
concave bearing surface are contoured (i.e., rounded) to facilitate
the assembly of the bearing 122 by the insertion of the inner ring
126 into the outer ring. As a result, the bore of the outer ring
128 (the smallest internal diameter perpendicular to the central
axis of the outer ring) is sized to facilitate insertion of the
inner ring 126 into the outer ring, and the load zone between the
inner and outer rings (which corresponds to the degree of
"wrap-around" of the outer ring around the inner ring) attainable
between the axial ends 133, 135 is limited accordingly. The
contoured axial ends 133, 135 and the limited wrap-around help
prevent damage to the outer ring 128 when the outer ring flexes
upon insertion of the inner ring 126 therein to assemble the
bearing 122.
[0014] In a particular embodiment, the outer ring 128 of the
bearing 122 has an outside diameter OD.sub.128 of about 150 mm
(about 5.9 inches (in.)), an axial width Wo.sub.128 of about 55 mm
(about 2.2 in.) and a bore of about 126 mm (about 5 in.), while the
inner ring 126 has a convex bearing surface 132 that conforms to a
spherical diameter Di.sub.126 of about 134 mm (about 5.2 in.) and
has an axial width Wi.sub.126 of about 70 mm (about 2.7 in.). The
inner ring 126 also has a bore defined by an interior, cylindrical
shaft bearing surface 134 having a diameter of about 100
millimeters (mm) (about 4 inches (in.)). When the bearing 122 is
used in a pivot joint of an A-arm frame for a haul vehicle, the
bearing performs poorly when exposed to impact loading, due to the
hard and brittle condition of the through-hardened steel inner and
outer rings. Any surface fracturing that occurs on a ring due to
sudden and high impact loads propagates through the outer ring,
usually leading to a failure of the pivot joint.
[0015] The bearing 22 according to this invention, as seen in FIGS.
4A and 4B, is a spherical plain bearing that includes an inner ring
26 disposed within an outer ring 28. The outer ring 28 has a
concave bearing surface 30. The inner ring 26 has a convex bearing
surface 32 and a bore defined by a shaft-bearing surface 34 that
engages the linking pin 20 (FIG. 2) that may be disposed therein.
The inner ring 26 is disposed within the outer ring 28 with the
concave bearing surface 30 engaging the convex bearing surface 32
and defining a bearing load zone between the concave bearing
surface and the convex bearing surface. The shaft-bearing surface
34 is provided with a lubrication groove 36 through which lubricant
(e.g., lubricating grease) can be provided to a linkage load zone
between the shaft-bearing surface 34 and the linking pin 20. The
lubricant may be provided to the linkage load zone via the
lubrication supply conduit 24 in the linking pin 20. The inner ring
26 also has one or more apertures 38 extending therethrough from
the shaft bearing surface 34 to the convex bearing surface 32, to
permit lubricant to flow from the linkage load zone to the bearing
load zone. However, unlike outer ring 128 of bearing 122, the outer
ring 28 does not have any lubrication aperture therethrough.
Accordingly, lubricant flowing in the bearing 22 from the linkage
load zone to the bearing load zone is not vented from the bearing
load zone through such apertures in the outer ring 28.
[0016] The outer ring 28 has a multi-fracture configuration, e.g.,
a double-fracture configuration, so the outer ring can be assembled
around the inner ring 26 and there is no need to flex the outer
ring to dispose the inner ring therein, or to contour the axial
ends of the concave bearing surface 30 of the outer ring 28 to
facilitate insertion of the inner ring into the outer ring. In
other embodiments, the outer ring 28 may have more than two
fractures.
[0017] In one embodiment, the bearing 22 according to the present
invention is a case-hardened bearing, i.e., both the inner ring 26
and the outer ring 28 are case-hardened, e.g., carburized, for
improved impact resistance and fracture toughness. As shown in FIG.
4B, the inner ring 26 and the outer ring 28 have hard,
wear-resistant cases 26a, 28a at their outside surfaces 26c, 28c.
The inner ring 26 and the outer ring 28 also have tough ductile
cores 26b, 28b at their respective interiors inside their cases
26a, 28a. For example, in one embodiment, the wear-resistant cases
have a hardness of at least about Rockwell C59 while the cores have
a hardness of not more than about Rockwell C49, for example, the
case may have a hardness of about Rockwell C56 to about Rockwell
C59 the core may have a hardness of about Rockwell C30 to about
Rockwell C49. While carburizing is mentioned as a means to provide
a case for the bearing 22, the invention is not limited in this
regard, as various means of case-hardening are known to one of
ordinary skill in the art, and any of such means may be employed to
provide the described case-hardening for the bearing 22.
[0018] In a particular embodiment, the outer ring 28 has an outside
diameter OD.sub.28 of about 150 mm (about 5.9 in.) and a width
Wo.sub.28 of about 55 mm (about 2.2 in.) along axis A (an "axial
width"). In addition, the inner ring 26 has a bore having a
diameter of about 100 mm (about 4 in.) and an axial width Wi.sub.26
of about 70 mm (about 2.7 in.). The inner ring 26 also has a convex
bearing surface 32 that conforms to a spherical diameter Di.sub.26
of about 134 mm (about 5.3 in.). However, in contrast to the prior
art bearing 122, in the bearing 22, the inner ring 26 and the outer
ring 28 each have an effective case 26a, 28a (e.g., the
perpendicular distance from the hardened outside surface 26c, 28c
to the farthest point at which a hardness of Rockwell C50 is
measured) of about 0.5 to about 1.6 mm (about 0.02 to about 0.06
in.) below the outside surfaces 26c, 28c, optionally about 1.1 to
about 1.6 mm (about 0.04 to about 0.06 in.) below the outside
surfaces 26c, 28c. Accordingly, the bearing is made from a
carburizing grade steel such as SAE8620H or the like. While
particular bearing dimensions have been described, the present
invention is not limited in this regard as other sized bearings can
also be employed without departing from the broader aspects of the
present invention.
[0019] It is believed that the hardened cases 26a, 28a provide
extended bearing life and the tough ductile cores 26b, 28b resist
the propagation of surface cracks through the inner ring 26 and the
outer ring 28, further improving the longevity of the pivot joint
18 relative to prior art pivot joints. In addition, the double
fracture construction of the outer ring 28 allows for a smaller
outer ring bore and a greater wrap-around of the inner ring 26 by
the outer ring than the single fracture construction of the prior
art bearing 122 permits, which enables the bearing 22 to have a
superior load-bearing capability relative to the prior art bearing
122.
[0020] FIG. 5 illustrates the use of the A-arm frame 10 of FIG. 1
on the housing 40 for the rear drive axle (not shown) of a haul
vehicle (not shown). The pivot joint 18 joins the A-arm frame 10
and the housing 40 to the vehicle frame 50, as known in the
art.
[0021] The terms "first," "second," and the like, herein do not
denote any order, quantity, or importance, but rather are used to
distinguish one element from another. In addition, the terms "a"
and "an" herein do not denote a limitation of quantity, but rather
denote the presence of at least one of the referenced item.
[0022] Although the invention has been described with reference to
particular embodiments thereof, it will be understood by one of
ordinary skill in the art, upon a reading and understanding of the
foregoing disclosure, that numerous variations and alterations to
the disclosed embodiments will fall within the spirit and scope of
this invention and of the appended claims.
* * * * *